BTN3A1 and neoplasm: Full activation of the γδ TCR requires pAg- and RhoB-dependent recruitment of BTN3A1 (together with BTN2A1) to the immunological synapse.37 In any case, it is clear that pAg accumulation in transformed cells is critically important for BTN-dependent activation of tumor-reactive Vγ9Vδ2T cells.